I have been told that to gain any more performance from my car, the best
thing to do would be to add a limited slip diff.or a torque differential.
Can somebody explain what these are and what they do.
Are they different things or are they just different names for the same
Also what sort of performance gain could I expect and what brand or model is
I currently have 192 BHP but I have been told that to increase the BHP any
more would make the car run 'lumpier'
I'm not sure what a "torque differential" is (maybe you mean a "Torsen") but
a limited-slip diff is a device that restricts the amount of sped
differential between the two axles. While it still allows one wheel to go
faster than the other for cornering, it transfers power away from the faster
wheel if the latter starts spinning freely.
There have been various designs, including ones with clutches or brake bands
of various designs. The Torsen (which has been described in many places, you
can undoubtedly find info on the Web if you look), is a specialized type of
limited-slip diff, using a special gear design. It has been used in some
high-end 4-wheel drive machines.
Lately these devices are being replaced with traction control, which uses a
computer to control a combination of ABS brakes and throttle retardation to
control torque to slipping wheels more precisely than any purely mechanical
device can do. Over here in North America we can get this on high-end Focus
models i.e. ZX5, ZTS and ZTW.
In an "open" differential like yours and mine, only one wheel receives power
at a time. In a limited slip differential, power is sometimes applied to
both wheels through a system of clutches. There are many variations among
manufacturers and models. If you are lighting up your tires constantly,
maybe a limited slip differential will help your performance but other than
that, I can't see what it will do. It is a big help in wet and slippery
conditions though. Good luck.
My 2001 Zetec 2.0 has ESP (Electronnic Stability Program) which acts not
unlike an LSD.
A basic differential allows your driven wheels to rotate at different
speeds, which means you can go round corners comfortably, but theoretically,
when travelling in a straight line, you don't need a diff. The problem when
you are trying to get a lot of power onto the road is that if one of the
tyres breaks traction, and you have a standard diff, you just get loads of
wheel spin on that wheel and your car doesn't go anywhere...
A limited slip diff prevents that by using a clutch system to limit the
speed difference between the two wheels. The degree of slip is varied by
adjusting the clutch pressure in the diff. Taken to the extreme, you can
have a totally locked diff, which is going to allow you to get maximum power
on the road. Problem with that is, that it is a dog when going round
corners. Also, the car gets very twitchy on bumpy roads, because if one
wheel leaves the ground for an instant, instead of that one spinning merrily
until it meets the tarmac again and the car continuing in a straight line,
the wheel in contact with the ground is still being driven and the car darts
In really fancy cars these days (for which read "world rally cars"), the
differentials are usually electronically controlled and the amount of slip
can be varied to suit the surface they are driving on.
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